Custom warning message does not show when called within a function

Question

Pascal Weller 2020-11-4

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/636120-custom-warning-message-does-not-show-when-called-within-a-function

评论： Mario Malic 2020-11-4

采纳的回答： Luna

在 MATLAB Online 中打开

Hello,

I have got difficulties to get custom warning messages to pop up in MATLAB's console.

Scenario:

I start execution of the main script. At some point it calls a function that is coded in a seperate .m file. From this called function I would like to display a warning. It executes the line where the warning is called but nothing shows up in the console. How do I make this warning to show up? Thanks in advance for your help!

Dummy code:

Main script which is run:

clear;
fd = 'test.h5'
...
foo(fd);
...

Script for function foo():

function foo(fd)
    if exist(fd,'file')
        warning('''%s'' already exists. Overwriting it.',fd);
        ...
    end
    ...
end

Btw: When I put a fprintf() or disp() or error() instead of the warning() it will show up in the console.

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Pascal Weller 2020-11-4

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Thanks for the quick response. Your prediction was accurate.

>> warning;
All warnings have the state 'off'.

For anyone facing the same issue: Here is how to enable all warnings:

warning('on');

Steven Lord 2020-11-4

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To probe the warning state:

warning query

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Answer 1

Luna 2020-11-4

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/636120-custom-warning-message-does-not-show-when-called-within-a-function#answer_534030

编辑：Luna 2020-11-4

在 MATLAB Online 中打开

I agree with Walter, put that code on command window to get all warnings on:

warning all on;

Be sure that your if statement result is true. I recommend you to try this first:

function foo(fd)
  if exist(fd,'file') == 2 % this is about exist function outputs. Check all the output states.  if it is 2, that means file exists.
    warning('''%s'' already exists. Overwriting it.',fd);
  else
    warning([fd, ' file does not exist.']);
  end
end

Here is the link for exist function documentation:

exist

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Mario Malic 2020-11-4

It looks like that if expression is true when expression result is nonempty and contains only nonzero elements (logical or real numeric). Otherwise, the expression is false.

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